Wireless communication networks are widely deployed to provide various communication services such as voice, video, packet data, messaging, broadcast, etc. These wireless networks may be multiple-access networks capable of supporting multiple users by sharing the available network resources. Examples of such multiple-access networks include Code Division Multiple Access (CDMA) networks, Time Division Multiple Access (TDMA) networks, Frequency Division Multiple Access (FDMA) networks, Orthogonal FDMA (OFDMA) networks, and Single-Carrier FDMA (SC-FDMA) networks.
A wireless network may support communication for a number of terminals. A terminal may place an emergency call in response to an emergency event. An emergency call is a call for emergency services (e.g., police, fire, medical, or other emergency services) and may also be referred to as an emergency services call. An emergency call may be initiated by a user dialing a well-known emergency number such as “911” in North America or “112” in Europe. It may be desirable to efficiently exchange signaling between the terminal and the wireless network for the emergency call.
eCall refers to an in-vehicle emergency call service. In the event of a collision involving the vehicle, the eCall In-Vehicle System (IVS) establishes an emergency call via a mobile network (also referred to as a wireless network or a cellular network) to emergency agencies, e.g., a Public-Safety Answering Point (PSAP). The IVS can be provisioned for “eCall-only” service or for “mixed-mode eCall” service. In “mixed-mode eCall” service, the system can be used to perform emergency eCalls as well as non-emergency, subscription-based calls. In “eCall-only” mode, the system can only be activated to make eCalls.
More particularly, dedicated eCall devices, such as those associated with a vehicle and designed for the sole purpose to make emergency calls in the event of an accident, are generally referred to as devices that operate in “eCall-only mode.” That is, eCall-only mode requires at least that the device does not perform mobility management procedures, including registration on a Public Land Mobile Network (PLMN), except when the device is attempting to initiate and during an emergency call, or when the device is attempting to initiate a test or reconfiguration connection.
An IVS in eCall-only mode does not register on the mobile network before the eCall is triggered. In case of an eCall emergency trigger, two operations are performed: (1) the IVS has to register on the mobile network and then (2) the IVS initiates the eCall emergency call. Conventionally, registration on the mobile network for an eCall is performed with the same priority as non-emergency calls. Conventional registration of the IVS on the mobile network may lead to a delay in placing the emergency call. It is critical that an IVS in eCall-only mode be able to successfully register as fast as possible after an incident triggers an eCall.